Alcohol intake and variations in blood pressure by day of examination.

The patterns of drinking and variations in blood pressure and gamma-glutamyl transferase (GGT) by day of examination have been examined in a large prospective study of cardiovascular disease in 7,735 middle-aged men drawn from general practices in 24 British towns. Overall, mean systolic and diastolic BP levels, as well as the prevalence of measured hypertension, were significantly higher on Mondays and lower on Fridays than on other weekdays. Among occasional, moderate weekend (3-6) and heavy weekend (greater than 6 drinks/day) drinkers, although mean BPs were higher in the heavier drinkers, there was little variation in BP from Monday to Thursday in these groups. In all three groups there was a significant fall in mean BP and in the prevalence of hypertension on Friday, more apparent for systolic than for diastolic pressure and more marked in older men. Among daily drinkers, BP tended to be high on Mondays but was not particularly low on Fridays. Heavy weekend drinkers had higher daily BPs than moderate daily drinkers except on a Friday, even though the estimated total weekly intake was similar. The variations in BP by day of examination were not mirrored by changes in GGT concentrations. The different effect of daily and weekend patterns of drinking on BP may explain some of the discrepancies observed between different alcohol-blood pressure studies. Findings from this study have important implications for the detection of hypertension in populations as well as for clinical practice.